Arc-welding torch



Dec. 5, 1950 D. c. GIRARD ETAL 2,532,807

ARC WELDING TORCH Filed Dec. 29, 1948 2 Sheets-Sheet l Dec. 5, 1950 D. c. GIRARD ETAL ARC WELDING TORCH Filed Dec. 29, 1948 INVENTORSv 36am C czfzz BYCZML 750626@ S w NS i mw i 05 @w Patented Dec. 5, 1950 UNITED STATES PATENT OFFICE 11 Claims. (o1. 21e-14) This invention relates, generally, to arc welding systems, and it has particular relation to gas shielded arc Welding in which the arc is stabilined by superimposed high frequency.

Among the objects of this invention are: To transmit the stabilizing high frequency to the welding arc with a minimum of loss and maximum efficiency and yet avoid undesirable radio interference; to transmit the stabilizing high frequency in such manner as to avoid overheating of the conductors carrying the same; to employ a cc-a'xial cable for transferring the stabilizing high frequency from the high frequency generatcr to the arc; to apply the high frequency across an inductor adjacent the arc; to connect the inductor in series with and immediately adjacent to the arc and to pass the welding current therethrough; to connect the inner lead of the co-axiai cable to the arc end of the inductor; to position the inductor at the end of an electrode holder with the electrode carried thereby providing one arc terminal; to supply an inert gas through the electrode holder and around the electrode and the arc; and to provide a hand hold on the electrode holder so located as to avoid affecting the application of' high frequency to the arc by the presence of the operators hand.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements, circuit connections, and arrangement of parts which will be exemplied in the description hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention, reference may be had to the following detailed description, taken together with the accompanying drawings, in which:

Figure l illustrates, diagrammatically, the circuit connections which may be employed in practicing this invention and which are disclosed and claimed in application Serial No. 67,795, flied December 29, 1948, now forfeited;

Figure 2 is a View, partly in side elevation and partly in section, of a welding torch and a portion of a composite cable extending therefrom Which may be employed in conjunction with the system illustrated in Figure l;

Figure 3 is a longitudinal sectional viewv of the welding torch illustrated in Figure 2; and

Figure 4 is a detail sectional View, taken along the line 4--4 of Figure 3.

Referring now particularly to Figure 1 of the drawings, it Will be observed that the reference character I designates a source of alternating current, such as a 220 Volt 60 cycle source. It

will be understood that other voltages and frequencies can be employed, the particular values specified being for illustrative purposes only. The source it may be connected by line switches II and a line contactor, shown generally at I2, to energize a primary Winding I3 of a welding transformer that is shown, generally, at I4. The welding transformer I includes a secondary winding I5 Whose open circuit voltage may be of the order of eighty to ninety volts. The line contacter i2 includes an operating Winding I2w, normally closed contacts 32a. whose function will be described hereinafter, and normally open contacts i213 and' ic. It will be observed that the contacts i2b, when closed, serve to connect the primary winding I3 for energization to the source it when the switches II are closed. Contacts I2C are provided to connect a capacitor It across 1the primary winding I3 for power factor correction.

r'h'e secondary winding l5 of the welding translformer it may be connected by conductors il and IS to supply current for maintaining a Welding arc I9 between an" electrode 2t, which may be of the non-consumable type, and Work 2l on which the welding operation is to be performed. As will appear hereinafter, inert gas, such as argon, may be supplied through a conduit 22 around the electrode 253 and the arc I9 in accordance with conventional shielded arc Welding practice.

Since the welding arc I9 is supplied from the secondary Winding i5 of the welding transformer i4 with relatively low frequency alternating current, difficulty is encountered in striking and maintaining the arc. The tungsten electrode 20 should not touch the work 2l except .to a very minor extent for it will be contaminated and interfere with proper operation. In order to assist in striking and maintaining the arc provision is made for superimposing on it a current of a relatively high frequency. For this purpose frequencies in the band from 27.16 to 27.43 rnegacycles have been set aside tentatively. In accordance with the present invention a frequency of 27.32 megacycles has been chosen from this permissible band of frequencies for stabilizing the operation of the arc i9.

Also in accordance With this invention, the stabilizing high frequency is supplied to the arc i9 in close proximity thereto. For this purpose an inductor 23 is connected between the Welding electrode 2? and the conductor il', as' shown. The inductor 23 is in the form of a tubular helix and, as will appear hereinafter, is arranged to have a coolant circulated therethrough for the purpose of removing heat from it and also from the parts adjacent the Welding electrode The inductor 23 has terminals 2li and 25. It Will be noted that the terminal 2Liis immediately adjacent the electrode 20 while the terminal 25 provides for connection to the welding lead or conductor Il.

The stabilizing high frequency is applied across the inductor 25 by means of a co-aXial cable that is shown, generally, at 25. It will be noted that the inner conductor 2l of the co-axial cable 26 is connected to the terminal 2li of the inductor 23 which is adjacent the electrode 2i] and the arc I9. The outer conductor 2% of the co-aXial cable 2e is connected to the other terminal 25 of the inductor 23. lf desired a variable capacitor may be connected across the inductor 23 to acljust the tuning thereof. It will be understood that the length of the co-aXial cable 26 is chosen with respect to the wave length of the stabilizmg frequency employed so that the high frequency current is transmitted therethrough with a mlmmum of loss and a maximum of efficiency. Overheating of the co-axial cable 23 is avoided. At the same time sufficient power is available across the inductor 23 to provide the desired stabilizing effect on the arc I5.

The conductors 2l and 23 which comprise the co-aXial cable 25 may be connected through capacitors 33 and 5e to an inductor 35. As illustrated the connections between the capacitors 33 and 3a and the inductor 35 are variable in order to permit adjustment of the tuning as may be required. The inductor 35 forms a part of a selfrectifying self-excited high frequency generator which is indicated, generally, at 36. The inductor 35 has a center tap, as shown, which is connected through a radio frequency choke coil 3l to ground at 38.

The generator 35 includes a double triode electric valve 35 which is of known design and construction. Type 304 TL has been found satisfactory for the purposes of the generator S5. It will be understood, however, that two separate single triode valves can be employed, if desired, in lieu of the double triode electric valve 39 illustrated.

The valve 39 includes an anode or plate 40 and a control grid fi i, these being connected, as shown, to theends of the inductor 35. The valve 39 also includes a pair of hot cathodes i2 which may be heated by secondary windings 53 of a filament transformer, shown generally at 44, which has a primary winding e5.

Any suitable means can be provided for energizing the primary winding 55. As shown, a switch 46 is employed for connecting the primary winding 45 for energization across a secondary Winding 4i, operating at 110 volts, which forms a part of a transformer, shown generally at 48. The transformer d3 has a primary windingV 49 which may be connected for energization across the source Ii! when the switches II are closed. In addition the transformer i8 has a low voltage secondary winding 55 arranged, as indicated, to operate at about seven volts, and used for a purpose to be described presently.

Capacitors 53 serve to interconnect the hot cathodes 42 and their mid point is connected to ground at 54 in accordance With conventional practice.

As indicated, the generator 36 is of the selfrectifying type. In order to accomplish this, radio frequency choke coils 55 interconnect the circuits to the hot cathodes 152 with a secondary winding 56 of a plate transformer that is indicated, generally, at l. A primary Winding 58 forms another part of the transformer 5I and it is arranged to be connected in a manner to be described presently for energization across the secondary winding SV' of the transformer 48.

It is desirable that the high frequency generator 36 function only during the time that the arc I9 is maintained between the electrode 29 and the Work 2i. This reduces the likelihood of radio interference since there is none when the generator 36 is not functioning and emission is at a minimum when the arc I9 is being maintained. In order to initiate the generator 36 in operation when it is desired to strike the arc i9 a start relay, shown generally at 59, is provided. The start relay 59 includes an operating winding 59m, normally open contacts 59a and normally closed contacts 59h.

A response to the operation of the high frequency generator 35 may be provided by a high frequency generator relay that is shown, generally, at B8. The relay I has an operating winding 5010 and'normally open contacts Gila and Stb. As shown, the operating winding 60u;` is connected between a mid point of the secondary Winding 55 and ground 6 I.

In describing the functioning of the system shown in Figure 1, it will be assumed that inert gas is being supplied through the conduit 22 and that the necessary coolant is being circulated through the inductor 23. Also it will be assumed that the switches I I and i6 have been closed and that the line contactor I2 and relays 59 and 69 are in the deenergized or dropped positions shown in the drawing. The impedance of secondary winding i5 is high enough to prevent energization of the winding 5910 therethrough. The operator romentarily touches the electrode 2D on the work As soon as the electrode 20 engages the work 2! a circuit is completed for energizing the operating winding 59u: of the start relay 59. This circuit may be traced from the low voltage secondary winding of the transformer 48, through conductor G2, operating winding 5910, conductor 53, conductor I8, work-2i, electrode 20, inductor 23, conductor Il, conductor IISG, normally closed contacts I2a and conductor 65 to the other side of the low voltage secondary winding 55. It will be apparent that the operator has to contend here with only a relatively low voltage, for example a voltage of the order of seven volts, which, as far as he is concerned, is entirely harmless.

As soon as the operating winding 59w of the start relay 59 is energized in the manner just described, the circuit to the operating winding i210 of the line contactor I 2 is opened at contacts 59h and at contacts 59a a circuit is completed for energizing the primary winding 58 of the plate transformer 5l. This circuit may be traced from one terminal of the secondary winding 4i of the transformer 48 through conductors 65 and 61, primary winding 58, conductor 68, contacts 59a and conductors 59 and 70 to the other side of the secondary winding l'l. Plate potential now is applied to the valve 39 and suiicient current flows through the operating winding 59u) of the generator relay 5i! to close its contacts 69a and SEIb.

Nothing further happens until the operator withdraws the electrode 2B from the work 2l while maintaining it close thereto so that the arc I9 now provided solely by the high frequency current -will continue. However, the

previously traced circuit for energizing the operating Winding 59w of the start relay 59 is opened and this relay drops. Although contacts a are opened by the dropping of start relay 59, the circuit for energizing the primary winding 58 of the plate transformer 51 is maintained through contacts` 80ay ofthe generatorv relay' 60a It will be observed that' the` contacts 59aarey connected in parallel with the contacts 60a by conductors |58Y and 13.

The dropping of theA start relay 59'completes a circuit at 59h for energizing the operating winding |2w of the line contacter |21; This circuit may be traced from one side ofA thel secondary winding 41 of the transformer 48 through conductorV 66, contactsV 50o, conductor 14, contacts 59h, conductor 15, opera-ting winding |220v and conductor 1|'lA to the other side of the secondary winding 41.

The line contactor- |42l now picks up and at contacts |21)` and I2C closes the circuits forenergizing the primary winding t3 of the welding transformer |4- andv connecting the capacitor It thereacross. Welding current now is induced in the secondary winding of the weldingk transformer |^4 and it ows through the conductors or welding leads |=`l'- and |'8 and the inductorV '.23A to provide the required current for the arc |$l which now is being stabilized' by the superimposed high frequency' from the generatorv 35.

Since, contacts |"2a are opened when the line contactor l2 is in the operated position, no current can flow through the operating winding 59u). of the startl relay 59. Ity will bev noted that the Winding w of the generator relayy `8G is conneeted by a conductorl 1'6 to the midpoint of the secondary winding 5,6 and by a conductor 1'! to ground 6|.

The Welding operation ceases when the operator moves the electrode 2U sufficiently far from the work. 2| so that the arc cannot be sustained. This action then unloads the generator 315 to ak suflicient extent so that the current 'ow through the plate circuit is reduced and, as a result, winding @tw of the generator relay SII is deenergized sufficiently to permit its contacts 38a and Stb tor be opened- TheV previously traced circuit for energizing the primary winding 58 of the plate transformer 51 through contacts 60a is opened and it is deenergized. At contacts 6013 the energizing circuit for the operating winding |210 of the line contacter |2 isY opened and it drops. The system now is restored to the initially assumed' position and', on resumption of welding4 operations, the cycle just described is repeated;

Referring now particularly to Figures 2, 3 and 4 of thev drawings, it will be observed that the reference character S designates, generally, a preferred' form of gas shielded arc torch which may be employed` in conjunction with the system illustrated in Figure l and described hereinbefore. The torch 80 includes a hollow cylindrical handle 8| which maybe formed of' insulating materialsuch as a phenolic condensation product. At its forward end it is provided with ametallic fitting or plug 82. which is joinedto a cylindrical metallic housing 83- that extends generallyl transversely thereof. has; al central opening 84 with which the gas inlet 22 communicates for supplying an inert gas around the electrode 2|! and the arc I9 in the manner described previously. The inert gas iiows through a longitudinally extending passageway 85 around jaws 86 which serve to grip the electrode 2t and provide electrical contact therewith. A conical throat member 81 of suitable heat resisting material, such as lava or porcelain, surrounds the jaws 86 and serves to direct the flow of gas over the electrode 2|! and around the arc I9.

The housing 83 It will be noted@ that the cylindrical? metallic housing 83 has an annular recess 30 which is closed by' a metallic sleeve- 9|. construction providesa coolingV chamber through which a coolant, such as water, mayv bel circulatedf for removing heat from the torch 8U. It will be understood' that a Water inlet conduit 92;, Figure 4-3 communicates with the annular recess 9U for supplying theV coolant thereto. The coolant is withdrawn fromY the annular recess 981 through a" conduit 931 and through theinductor 23 which; as shown more` clearly in Fig; 3L of thedrawings, is in the form ofa tubular` helixy the longitu'dinal axis of which coincides with the longitudinal axis or the handle 8|. A Wateroutlet conduit 9`4; Figure 4, lis connectedV to the inner end of the tubular inductor 2-3 and serves to withdraw the coolant therefrom. It Will be observed Figure Bthat the conductor l1, preferably in the form of a strandedv conductor or cable, isconnected to the inner end of the inductor 23 for supplying welding current therethrough to the electrode 20 throughv the metallic tti'ng 82 and cylindrical metallic housing 83. The stranded conductor 1 is positioned inside of a conduit 94" which isV connected to the conduit $4; An insulating sleeve 95 surroundsthemetallichousing 83, as shown.

Within the outerend of thehandlel Slthe tubular inductor 2'3' is mounted on a spirally groovedinsulating core 98- and' isv surrounded by a suitableinsulating sleeve 99.

It will be observed that the flexible conductor |1, inert gas conduit 22, the co-axialcable 263 the Water inlet conduit 92 and the water outlet conduit- 94 are located within a flexible sleeve |U0- whichextends out of the rear end of the cylindrical handle' 8|. It willy be-understood that the'portions of the gas' conduit 22; co-axial cable 26, and water inlet and outlet conduits 92 and 94 are flexible Where they' are coextensiver with the sleeve I0; These parts are of" a lengthY necessary to provide the required connections to the various pieces of apparatus illustratedl diagramnatically` in Figure 1 and described hereinbeore.

Intermediate the ends of thecylindrical handle 8| there is provided a ring HHV which maybe secured in position by set screws` |62. The ring |0| serves to separate the forward end ofthe handle 8| from the rear or hand: hold portion |03. It will be noted that the hand hold portion |03 isy entirely beyond the inductor 23 or, in other words, is not coextensive therewith: The

, reason for this isL to prevent the hand or hands of the Ioperator from aiecting the tuning of the inductor 23 byy being placed'therearound outside of the portion of the handle 8| which is coextensive therewith.

In Figure 3 the connection of the inner conductor 21 of theY co-axial cable 2S to the metallictting 82' is shown. The outer conductor` 28 of the co-axial cable 25 is connected to the inner end of the inductor 23 by aplate m4. Thus; as previously described, the conductors which comprise the co-axial cable 2B' are connected across theinduot'or 23 with the inner conductor 21`beii'1g connected t'o the end thereof whichv is immediately adjacent the welding electrode 2'0.

Since certain changes can be made in the foregoing construction and different embodiments of the invention can be made witho-ut departing from the spirit and scope thereof, Iit is intended that all matter shown in the accompanying drawings and described hereinbefore shall be inter- 7 preted as illustrative and not in a limiting sense.

What is claimed as new is:

1. For combination in an arc welding system wherein the arc is a low frequency alternating current arc and is stabilized by high frequency current of the order cf several megacycles superimposed thereon, an inductor in substantially as close proximity to the arc as it is physically possible to position the same, and circuit means consisting of a non-radiating transmission line for connecting said inductor for energization across the high frequency current source. l

2. For combination in an arc welding system wherein the arc is a low frequency alternating current arc and is stabilized by high frequency current cf the order of several megacycles, superimposed thereon, an inductor in substantially as close proximity to the arc as it is physically possible to position the same, circuit means for connecting said inductor in series with the welding current source, and circuit means consisting of a non-radiating transmission line for connecting said inductor for energization across the high frequency current source.

3. For combination in an arc welding system wherein the arc is a low frequency alternating current arc and is stabilized by high frequency current of the order of several megacycles superimposed thereon, an inductor formed by a tubular helix in substantially as close proximity to the L arc asY it is physically possible to position the same, circuit means for connecting said inductor in series with the welding current source, means connected to said tubular helix to cause a coolant to flow therethrough, and circuit means consisting of a non-radiating transmission line for connecting said inductor for energization across the high frequency current source.

4. For combination in an arc welding system wherein a low frequency arc is stabilized by superimposed high frequency of the order of several megacycles, an inductor in series with the arc and in substantially as close proximity to the arc as it is physically possible to position the same through which the low frequency flows, and a non-radiating co-axial cable tuned to said frequency for connecting said inductor across a source of high frequency, the inner electrode of said cable being connected to said inductor adjacent the arc.

5. For combination in an arc welding system wherein a low frequency arc is stabilized by superimposed high frequency of the order of several megacycles, an inductor formed vby a tubular helix in series with the arc and in substantially as close proximity to the arc as it is physically possible to position the same through which the low frequencyilows, means connected to said tubular helix to circulate a coolant therethrough, and a non-radiating co-axial cable tuned to said frequency for connecting said inductor across a source of high frequency, the inner electrode of said cable being connected to said inductor adjacent the arc.

6. For combination in a low frequency alternating current circuit an inductor in the form of a tubular helix through which the low frequency alternating current fiows, non-magnetic insulating means supporting said inductor, circuit means connecting said inductor across a source of high frequency current of the order of several megacycles whereby the same flows through the outermost part thereof, and means connected to said tubular helix to cause a coolant to oW therethrough.

7. A gas arc torch for welding with an electrode comprising, in combination, a tubular handle of insulating non-magnetic material, mounting the electrode at one end of said handle, a conduit extending through said handle to supply a gas around said electrode and the arc, an inductor within said handle at said one end with its outer end connected to said electrode and its inner end for connection to one terminal of a low frequency alternating current source, non-magnetic insulating means supporting said inductor, and circuit means extending through said handle for connecting said inductor for energization across a source of high frequency current of the order of several megacycles to stabilize the low frequency arc.

8. The invention, as Set forth in claim 7, wherein the handle extends beyond the inductor sufliciently far to provide a hand hold.

9. The invention, as set forth in claim 7, wherein the inductor `is in the form of a tubular helix, and inlet and outlet conduits extend through the handle and connect to opposite ends of said helix for circulating a coolant therethrough.

10. The invention, as set forth in claim 7, wherein the circuit means is a co-axial cable with the inner lead connected to the inductor adjacent the electrode.

11. In combination, a gas arc torch for welding with an electrode, a tubular handle for carrying said electrode at one end; a composite cable extending from the other end of said handle including a conduit for supplying a gas around said electrode and the arc, a welding current conductor, a co-axial cable, and inlet and outlet coolant conduits; and an inductor in the form of a tubular helix carried by said handle adjacent said electrode with one end connected thereto, said Welding current conductor being connected to the other end of said inductc-r, said co-axial cable being connected across said inductor with the inner lead connected to the electrode end, said coolant conduits being connected to the ends of said tubular helix.

DEAN C. GIRARD. FRANK T. ROACH.

REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 1,973,122 Stoddard Sept. 11, 1934 1,982,327 Smith Nov. 27, 1934 2,036,233 Pakala Apr. 7, 1936 2,093,821 Southgate Sept. 21, 1937 2,336,177 Howard et al. Dec. 7, 1943 OTHER REFERENCES The Welding Journal, May 1947, page 411.

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